Distribution pattern of soil microbial population in salt-affected soils

Ragab, M. T.

doi:10.1007/978-94-011-1858-3_48

Cited by 21 publications

(8 citation statements)

References 4 publications

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“…This reflected the detrimental effects that soil salinity had on soil microbial activity. These results parallel the findings of Yuan et al (2007), and are in accordance with a pattern found in naturally occurring saline soils in which microbial biomass is typically negatively correlated with total soluble salt content (Ragab, 1993;Rietz and Haynes, 2003;Sardinha et al, 2003), but positively correlated with soil organic C content (Zahran et al, 1992). In this study, there was also a positive correlation between microbial biomass C and soil organic C (Table 6), possibly because MBC is a part of SOC (Li et al, 2004;Sparling, 1997).…”

Section: Soil Microbial Activitiessupporting

confidence: 93%

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Soil property and microbial activity in natural salt affected soils in an alternating wet–dry tropical climate

Iwai

Topark-Ngarm

2012

Geoderma

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Section: Soil Microbial Activitiessupporting

confidence: 93%

“…Salinity-induced degradation in soils is characterized by low soil organic C values (Ragab, 1993;Zahran et al, 1992). The total organic C content does not exceed 6 g kg − 1 at any site in either season.…”

Section: Soil Microbial Activitiesmentioning

confidence: 99%

Soil property and microbial activity in natural salt affected soils in an alternating wet–dry tropical climate

Iwai

Topark-Ngarm

2012

Geoderma

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“…It has been shown that salinity induces considerable stress on soil microorganisms (Sardinha et al, 2003). The total number of culturable bacteria has been shown to decrease with increasing soluble salt concentration (Polonenko et al, 1986;Ragab, 1993). However this is the first report on salinity effects on microbial community composition using molecular methods, which assess a greater proportion of soil bacteria than culture-dependent methods (Bakken, 1985).…”

Section: Discussionmentioning

confidence: 94%

Growth response of Atriplex nummularia to inoculation with arbuscular mycorrhizal fungi at different salinity levels

et al. 2005

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Chenopods are generally regarded as non-host plants for mycorrhizal fungi and are believed not to benefit from colonization by mycorrhizal fungi. Perennial Atriplex nummularia Lindl., growing under field conditions, showed a relatively high level of colonization by mycorrhizal fungi (10-30% of root length colonized) in spring and summer. Accordingly, two glasshouse experiments were designed to assess the effects of inoculation with mycorrhizal fungi (with a single species or a mixture of different species) on growth, nutrient uptake, and rhizosphere bacterial community composition of A. nummularia at high and low salinity levels (2.2 and 12 dSm )1 ). Only low and patchy colonization by mycorrhizal fungi (1-2% of root length colonized) was detected in inoculated plants under glasshouse conditions which was unaffected by salinity. Despite the low colonization, inoculation increased plant growth and affected nutrient uptake at both salinity levels. The effects were higher at an early stage of plant development (6 weeks) than at a later stage (9-10 weeks). Salinity affected the bacterial community composition in the rhizosphere as examined by ribosomal intergenic spacer amplification (RISA) of 16S rDNA, digitization of the band patterns and multivariate analysis. The effects of inoculation with mycorrhizal fungi on growth of A. nummularia may be attributed to (i) direct effects of mycorrhizal fungi on plant nutrient uptake and/or (ii) indirect effects via mycorrhizal-induced changes in the bacterial community composition.

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“…These variations seemed to be related to the physicochemical characteristics of soils, the inherent type and diversity of microorganisms occurring in these soils [18,19,20].It was interesting to note that inspite of rise in salinity, even up to the levels of 26 and 28 dSm -1 in S3 and S4 soils, respectively, during the summer season, the soils supported considerable diazotrophic populations. The total count of bacteria is usually negatively correlated with the total soluble salts of saline soils [21], but positively correlated with organic carbon contents [21,22]. However, these soils might have their own bacterial communities, which have adapted to saline environments.…”

Section: Non-symbiotic Heterotrophic Diazotrophic Bacterial Counts Ofmentioning

confidence: 99%

Studies on Non-Symbiotic Diazotrophic Bacterial Populations of Coastal Arable Saline Soils of India

et al. 2011

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The effect of fluctuations of salinity in three different seasons on diazotrophic populations and N 2 fixation in six mono cropped rice field soils of the coastal region of the Gangetic delta of West Bengal, India, was studied. The average pH, ECe, organic carbon and total nitrogen of the soils ranged from 4.99-7.08, 2.02-19.58 dSm -1 , 4.68-12.03 g kgand 0.44-1.70 g kg -1 , respectively. The average log colony forming units of the bacterial populations and N 2 -fixation in the soils varied from 4.61 to 5.86 and 2.74 to 4.52 mg N 2 fixed 50 ml -1 culture media respectively, with the lowest value recorded in summer. Recovery of microorganisms and N 2 -fixation gradually decreased with extraneous addition of NaCl in the culture media. All the eight isolates were Gram positive, spore and capsule formers. They could utilize glucose, sucrose, mannitol, starch, citrate and nitrate, and were catalase and gelatinase positive, but indole, methyl red and Vogues Proskauer reaction negative. The organisms produced alkaline reaction on TSI agar slant. The acetylene reduction assay of the isolates at 0 and 1% NaCl in the culture media were 4.51-164.52 and 1.72-100.6 nmole C 2 H 4 ml -1 culture media in 72 h, respectively. The isolates could fix 2.42-4.45 and 2.04-4.08 mg N 2 fixed 50 ml -1 culture media at 0 and 1% NaCl in the culture media respectively. 16S rDNA sequences of the isolates were similar to the species: Bacillus sp. isolate 28A, Bacillus sp. MOLA 87, Bacillus sp. By113 (B)Ydz-dh, Bacillus sp. PN13, Bacillus licheniformis strain RH101, Bacterium Antarctica 14, Bacillus sp. PN13 and Bacillus megaterium.

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Distribution pattern of soil microbial population in salt-affected soils

Cited by 21 publications

References 4 publications

Soil property and microbial activity in natural salt affected soils in an alternating wet–dry tropical climate

Soil property and microbial activity in natural salt affected soils in an alternating wet–dry tropical climate

Growth response of Atriplex nummularia to inoculation with arbuscular mycorrhizal fungi at different salinity levels

Studies on Non-Symbiotic Diazotrophic Bacterial Populations of Coastal Arable Saline Soils of India

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